1. Field of the Invention
The present invention relates to a sheet feeding apparatus and processes generally, and, more particularly, to a paper feeding apparatus and process in an office automation system capable of preventing sheets of paper from deviating from the paper feeding apparatus during continuous feeding of the paper, realigning the paper for feeding while preventing more than one sheet from being fed and preventing occurrence of curl in the stationary sheets of paper.
2. Description of the Related Art
Office automation machinery includes image formation devices such as printers, facsimile transmission units, photocopies and scanners. Printers are used for creating documents by printing characters, symbols and images onto one exposed surface of a printable medium such as a cut sheet of paper that is fed into and transported through the printer, while scanners are used for reading and storing in image files characters, symbols and images from documents that have been fed into the scanner. A multi-functional office automation machine with the functions of both a printer and a scanner makes it possible for users to selectively use either one of these functions, in accordance with the desires of the user.
Since the aforementioned printers, scanners, or multi-functional office automation machines require the feeding of paper during printing, facsimile transmission, photocopy duplication or scanning, they are often equipped with some sort of paper feeding apparatus that feeds one or more sheets of paper to the machine. Papers stored in a paper tray, for example, are fed by the paper feeding apparatus, and are usually moved to a printing unit of the printer, photocopier or facsimile, or to the scanning unit of the scanner by the coordinated operation of several feed rollers. After images and characters of the document are either printed on the blank surface of the paper or read from the printed side of the document, the paper is then extracted through an outlet of the machine.
When printing or scanning is preformed by such paper feeding apparatus, the paper is usually continuously fed by one sheet after another sheet, beginning with the uppermost sheet in the stack of paper that is held by the apparatus. We have noticed however, that conventional paper feeding apparatus has an undesired tendency to simultaneously feed those sheets of paper that are stacked just below the uppermost sheet, together with the uppermost sheet, during the feeding operation of the apparatus. We have also found that this phenomenon occurs when the paper below the uppermost sheet is very thin, or has a curl at a particular portion of the sheet. I have also discovered that when a sheet of paper with such a curl is in contact with a separation finger that is disposed at both lower portions of the paper tray, the ears of the paper are all too often folded. This, in my opinion, frequently causes that sheet of paper to precipitate a problem during the course of the feeding operation, such as a paper jam within either the feeding apparatus for the image formation machine, a printing error, or scanning error. Moreover, when the paper is stored for a long time in a state standing at the feeding apparatus, a few sheets of the paper are abnormally fed to the separation finger along the resistance rib of the main frame of the paper feeding apparatus. Therefore, when the paper which is very thin or has a curl, is fed under the circumstance, the aforementioned abnormal paper feeding occurs.